In many languages the sequential ordering of prenominal or postnominal adjectives is tightly constrained, and the preferred sequences are either identical or monotonically related to one another. What are the determinants of adjective ordering in individual speech behavior, and are there common factors across languages which may account for the similarities of this design feature across languages? Three sets of studies are proposed to shed light on these questions. The first employs an experimental language learning paradigm to determine which of several characteristics of adjectives are capable of controlling adjective ordering in a language production task. The second employs an analogous paradigm to determine which of those adjective characteristics mediate the effects of adjective ordering upon speed and accuracy of comprehension. The third assesses the extent to which adults are able to use feedback in a communication context to modify their adjective ordering in maximally useful ways. These studies should enable us to answer theoretically interesting questions concerning the relations between individual language processing mechanisms and the design features of natural languages.